/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package com.foxinmy.weixin4j.logging;

/**
 * Creates an {@link InternalLogger} or changes the default factory
 * implementation. This factory allows you to choose what logging framework
 * Netty should use. The default factory is {@link Slf4JLoggerFactory}. If SLF4J
 * is not available, {@link JdkLoggerFactory} is used. You can change it to your
 * preferred logging framework before other Netty classes are loaded:
 * 
 * <pre>
 * {@link InternalLoggerFactory}.setDefaultFactory(new {@link Log4JLoggerFactory}());
 * </pre>
 * 
 * Please note that the new default factory is effective only for the classes
 * which were loaded after the default factory is changed. Therefore,
 * {@link #setDefaultFactory(InternalLoggerFactory)} should be called as early
 * as possible and shouldn't be called more than once.
 */
public abstract class InternalLoggerFactory {
	private static volatile InternalLoggerFactory defaultFactory = newDefaultFactory(InternalLoggerFactory.class
			.getName());

	private static InternalLoggerFactory newDefaultFactory(String name) {
		InternalLoggerFactory f;
		try {
			f = new Slf4JLoggerFactory(true);
			f.newInstance(name).debug(
					"Using SLF4J as the default logging framework");
		} catch (Throwable t1) {
			f = new JdkLoggerFactory();
			f.newInstance(name).debug(
					"Using java.util.logging as the default logging framework");
		}
		return f;
	}

	/**
	 * Returns the default factory. The initial default factory is
	 * {@link JdkLoggerFactory}.
	 */
	public static InternalLoggerFactory getDefaultFactory() {
		return defaultFactory;
	}

	/**
	 * Changes the default factory.
	 */
	public static void setDefaultFactory(InternalLoggerFactory defaultFactory) {
		if (defaultFactory == null) {
			throw new NullPointerException("defaultFactory");
		}
		InternalLoggerFactory.defaultFactory = defaultFactory;
	}

	/**
	 * Creates a new logger instance with the name of the specified class.
	 */
	public static InternalLogger getInstance(Class<?> clazz) {
		return getInstance(clazz.getName());
	}

	/**
	 * Creates a new logger instance with the specified name.
	 */
	public static InternalLogger getInstance(String name) {
		return getDefaultFactory().newInstance(name);
	}

	/**
	 * Creates a new logger instance with the specified name.
	 */
	protected abstract InternalLogger newInstance(String name);
}
